Cavity detection and choice of the best device

[MASH]

Hi,
I want some advise on which devise to use to detect medium to large cavities with average depth of 5-7 meters in sandy rocky soil. Previously i have purchased an electrical resistivity device called landmapper ERM01 from a company called Lanvisor. The device was not bad but as with most of the ERM devices the work and time needed for the detection was too much, plus the hassle of changing the location of the probes and the wiring and all that, then comes the final challenge of refining the readings and importing them to the software "i used RES2DINV". I had a lot of support from the company and did so much studying to be able to use the device but it just takes too much time and effort specially in the case of deep detection where you need to cover more length with the porbes to reach your depth.

I have decided to buy a new device and after doing some research on the net i found the following devices to chose from:

1- OKM Rover CII " http://www.okmmetaldetectors.com/pro...on.php?lang=en "
but i have came across bad reviews and comments on the OKM products .... Is it really that bad?

2- AEMP-14- Multi-frequency Electro-Magnetic Induction sounding " http://www.landviser.net/content/aem...ction-sounding "
its also a product of Landvisor (a company that i trust based on personal experience) but i still do not know anything about the technology and efficiency given that the device is not cheap and costs around 12,000 USD.

3- EasyRad GPR 20-400 MHZ " http://www.easyrad.com.ua/index.php?r=opis_en "
4- EasyRad GPR 500 MHZ - 1 GHZ " http://www.easyrad.com.ua/index.php?r=opis500_en "
I am also new to GPR but i have the feeling that it is the most promising device of all, but again im not sure if im right.

I need help on choosing the most suitable and efficient device from the above list of even any other suggestion that may guide me to the right direction.

Thanks and Regards

[Geo]

I have bad experience from OKM and i don't know anything about AEMP-14, so for me the GPR is the only solution but 5...7m depth is so much for the EasyRad GPR 20-400 MHZ. Maybe the EasyRad GPR 500 MHZ - 1 GHZ to has this ability.

[MASH]

I have bad experience from OKM and i don't know anything about AEMP-14, so for me the GPR is the only solution but 5...7m depth is so much for the EasyRad GPR 20-400 MHZ. Maybe the EasyRad GPR 500 MHZ - 1 GHZ to has this ability.

Thank you Geo, i will try to research the maximum depth achieved with the Easyrad GPRs, however if any one can help me with info on the AEMP-14 and how it works i would be very thankful, again or suggest any other suitable device.

[Geo]

From what i understood the detctor is based on a IB coil so maybe it is a T/R detector, but i don't think that can detect anomalies at 10m depth as they say at site. Maybe 2... 3 m in the ground.
Of course is my opinion.

[kaminae]

AEMP-14 - is ex Nemfis instrument discussed here before. It's just instrument for profiling.
GPR - will be much more better for You.

[Bigstarman]

EasyRad GPR 20-400 MHZ will help solve your problem.
Take the Pro Plus kit and software RadMax.
EasyRad GPR registers not only the cavity, but also dielectrics, such as amber. Watch the video
https://www.youtube.com/watch?v=eysprYETCnQ
https://www.youtube.com/watch?v=QVC6NWQmmHk

And don't forget. Modern GPR is a complex of three components - radar, computer, specialized software and a competent & experienced operator.
From this complex it is impossible to drop any components.

[Gmradar]

I would suggest a GPR unit but this may be a bit expensive. I know GSSI offers a radar with a 400MHz antenna and is at promotion right now at around 14k$. GSSI for me is by far the best GPR company.

If you want an EM device perhaps you could look around for either a profiler or a CMD from GF. The latter costs around 12k$

www.gmradar.com - your reliable subsurface supplier.

[Hemasri]

Rather than going to time domain radar look for freq.domain (or step freq. radar) for a deep penetration depth. I am using one (which is a tailor made), that penetrates 30m with 1.2m antenna (one for TX and other for Reciver), the freq. range is from 10MHz - 180 MHz. If you need more details contact me through [email protected]

Regards

Hemasri

[kamel]

Hi
I suggest you to use the ERT method,is better than the GPR,if the field is wet and if you use the GPR make sure the high frequency is recommended for the target shallower,it gives best resolution and and low depth of investigation, when the low frequency gives intermediate resolution and best depth of investigation. for me i m use the ERT method withe both arrays the dipole dipole and Wenner-Shlumberger of course the inter-electrode spacing is equal or smaller than the diameter of cavity in order to good delineate this anomaly (your cavity).

I have an experience with the ERT method and she gives to me best results always

Kind regards
Kamel